Bhagavad-gita 2.22 Soul changes body like a person changes garments

vasamsi jirnani yatha vihaya navani grhnati naro 'parani
tatha sarirani vihaya jirnany anyani samyati navani dehi ... BG 2.22
As a person puts on new garments, giving up old ones, the soul similarly accepts new material bodies, giving up the old and useless ones.

Change of body by the atomic individual soul is an accepted fact. After old age, the soul is transferred to another body. Transference of the atomic soul to another body is made possible by the grace of the Supersoul.

There are two kinds of souls - namely the minute particle soul (jivatma or anu-atma - limited in quality) and the Supersoul (Paramatma or vibhu-atma - unlimited in quality). This is also confirmed in Katha Upanishad (1.2.20) that states that both the Supersoul and the atomic soul are situated on the same tree of the body within the same heart of the living being. The Supersoul fulfills the desire of the atomic soul as one friend fulfills the desire of another.

In Mundaka Upanisha (3.1.1 & 3.1.2) and Svetasvatara Upanishad (4.6 & 4.7), soul and Supersoul are compared to two friendly birds sitting on the same tree. Of these two birds, one is captivated by the fruits of the material tree while the other is simply witnessing the activities of His friend.

Although they are friends, one is the Master and the other the servant. Forgetfulness of this relationship by the atomic soul is the cause of one's changing his position from one tree to another or from one body to another. This makes the atomic soul struggle very hard engrossed with anxiety and moroseness as the enjoyer of the fruits of the tree or of the material body.

As soon as the atomic soul agrees to accept the other bird as the supreme spiritual master the subordinate bird understand the glories of the Supersoul and becomes free from material desires and lamentations.

Krsna is the fountainhead of the Supersoul and Arjuna is the atomic soul, forgetful of his real nature. Krsna is like the witnessing bird and Arjuna the eating bird. Therefore Arjuna required to be enlightened by Krsna. Since Arjuna had turned his face towards his eternal friend, Krsna, he was understanding the Bhagavad-gita from Him and becoming free from lamentation.

Bhagavad-gita 2.18 - 2.21 Soul is unborn, eternal and does not die unlike the body

Material body is sure to come to an end. It is perishable in nature. It may perish immediately or after many years. It cannot be protected permanently or maintained indefinitely.

Spirit soul is immeasurable (aprameyasya), indestructible (anasinah) and eternal (nitya). Its dimension is extremely small to be measured and cannot be seen. Lord states "ukta" since this knowledge is authorized in Vedic literatures and ascertained by authorities (acarya).

Soul cannot be killed. When an embodied living entity is hurt by fatal weapon, the living entity within the body is not killed. It is only the body that gets killed. Soul is not slain when the body is slain. na hanyate hanyamane sarire.

Killing of the human body or animal slaughter is not encouraged by Vedic injunction. Also, killing of body without authority is abominable and punishable by the law of the state and the law of the Lord. In Manu-samhita lawbook for mankind, a murderer is supposed to be condemned to death so that in his next life he will not suffer for the great sin he has committed.

Arjuna however was engaged in killing for the principle of religion and hence was advised to fight. For the administration of justice, violence committed in the act of fighting under instructions from Krsna is permitted. This is similar to a surgical operation meant to cure a patient and not kill him.

For the soul, there is neither birth nor death at any time. He has not come into being, does not come into being and will not come into being. He has no past, present or future. He is unborn (ajah), eternal (nitya), ever-existing (sasvatah), primeval (puranah) and immutable (avyayam).

The soul is called steady or kuta-stha. The changes in the body do not affect the soul. He does not grow nor does he deteriorate like a tree. He does not become old as the body does. The soul also has no by-product or off-shoots. Body on the other hand appears to have by-products or children. However, even a child has different individual soul and the body develops because of the presence of soul.

In Vedanta-sutra the living entity is qualified as light because he is part and parcel of the supreme light or Supreme Spirit. As sunlight maintains the entire universe, spirit soul maintains the material body. As soon as the spirit soul is out of the material body, the body begins to decompose. Therefore it is the spirit soul which maintains the body.

Bhagavad-gita 2.17 Soul is perceived through consciousness pervading the body

avinasi tu tad viddhi yena sarvam idam tatam … BG 2.17 Consciousness is spread all over the body. Real nature of soul is perceived from this consciousness, which is the symptom of soul’s presence. sarvam means all over the body and tatam means pervaded. Consciousness pervades all over the body because of the soul.

Individual soul - Each and every living body is the embodiment of an individual soul. Everyone is conscious of the pains and pleasures of the body in part or as a whole. This spreading of consciousness is limited within one’s own body. The pains and pleasure of one body is unknown to another. Symptom of the soul’s presence is therefore perceived as individual consciousness.

Influence of the spirit soul is spread all over the body just as the active principle of some medicine spreads throughout the body. This influence is felt all over the body as consciousness. Therefore consciousness is the proof of the presence of the soul.

Size of soul is described in Svetasvatara Upanishad as one-ten-thousandth part of the upper portion of the hair point. When the upper point of a hair is divided into 100 parts and again each of such parts is further divided into 100 parts, each such part is the measurement of the dimension of the spirit soul. These individual particles of spirit soul are spiritual atoms. Such spiritual atoms are smaller than material atoms.

Innumerable - Spiritual atoms are innumerable in number. Soul is like very small spiritual spark emanating from fire. This is the basic principle of the material body. There are 84 Lakh different species in the material world having different bodily structure. Each body is embodied by individual spirit soul.

The atomic particles of the spirit whole are compared to the sunshine molecules. In the sunshine there are innumerable radiant molecules. Similarly, the fragmental parts of the Supreme Lord are atomic sparks or prabha of the rays of the Supreme Lord.

Location - As per Mundaka Upanishad, the atomic soul is floating in the five kinds of life air (prana, apana, vyana, samana and udana). It is situated within the heart and spreads its influence all over the body of the embodied living entities. When the soul is purified from the contamination of the five kinds of life air, its spiritual influence is exhibited. In hatha yoga, the five kinds of air encircling the soul are controlled by different kinds of postures. This liberates the minute soul from the entanglement of the material atmosphere.

Material scientists - Atomic soul can be perceived by perfect intelligence. Because the measurement of the atomic soul is beyond the power of appreciation of the material scientists, some of them assert that there is no soul. Medical science however admits that the heart is the seat of all energies of the body. They recognize the importance of red corpuscles of blood but they cannot ascertain that the source of the energy is the soul. The corpuscles which carry oxygen from the lungs to the cells of the body gather energy from the soul.

Example of SUN - Soul is full of knowledge or consciousness. Even if one does not find the soul within the heart, one can still understand the presence of the soul simply by the presence of consciousness. Sometimes we do not find the sun in the sky owing to clouds but the light of the sun is always there are we are convinced that it is daytime. As soon as there is little light early in the morning, we can understand that the sun is in the sky. Similarly, since there is consciousness in all bodies – whether human or animal – we can understand the presence of the soul.